Production of urea-ammonium sulfate

ABSTRACT

A PROCESS FOR THE PRODUCTION OF UREA-AMMONIUM SULFATE GRANULES FROM UREA AND AMONIUM SULFATE BY SEVERAL GRANULATION METHODS. THE PROPORTION OF AMMONIUM SULFATE IN THE MIXTURE WAS VARIED FROM 15 TO 70 PERCENT BY WEIGHT RESULTING IN PRODUCTS CONTAINING FROM 42 TO 29 PERCENT N AND 3 TO 17 PERCENT S, RESPECTIVELY, UNEXPECTEDLY, THE UREA-AMONIUM SULFATE MIXTURE IN THESE PROPORTIONS WERE FLUID ENOUGH AT 250* TO 325*F. TO BE PRILLED AND GRANULATED BY CONVENTIONAL MEANS. TYPICAL GRADES MADE IN CONTINUOUS-TYPE PILOT-PLANT WORK WERE 40-0-0-4S, 34-0-0-9S, AND 30-0-013S. MOST GRANULATION WAS CARRIED OUT BY OIL PRILLING OR IN A PUGMILL BUT AND TYPE OF GRANULATION METHOD, SUCH AS AIR PRILLING OR IN DRUM OR FLAKER, LIKELY WOULD BE FEASIBLE. WITH USE OF 99.5 PERCENT UREA SOLUTION AND SOLID AMMONIUM SULFATE, NO DRYING STEP WOULD BE REQUIRED. THE PRESENCE OF THE AMMONIUM SULFATE INCREASED THE STRENGTH OF THE GRANULES SIGNIFICANTLY. NO CAKING OCCURRED WHEN UNCONDITIONED 30-0-0-9S PRILLS WERE STORED IN BULF FOR 6 MONTHS. UNCONDITIONED PRODUCT OF 40-0-0-4S GRADE CAKED IN 3 MONTHS BUT STORAGE FOR THIS PERIOD WAS SATISFACTORY WHEN 2 PERCENT BY WEIGHT OF KAOLIN CLAY CONDITIONER WAS USED. THE CRITICAL RELATIVE HUMIDITY OF THESE PRODUCTS WAS IN THE RANGE 55 TO 60 PERCENT AT 86*F.

DEFENSI PLlGAlON UNITED STATES PATENT OFFICE Published at the request ofthe applicant or owner in accordance with the Notice of Dec. 16, 1969,869 O.G. 687. The abstracts of Defensive Publication applications areidentified by distinctly numbered series and are arrangedchronologically. The heading of each abstract indicates the number ofpages of specification, including claims and sheets of drawingscontained in the application as originally filed. The files of theseapplications are available to the publicfor inspection and reproductionmay be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to themerits of alleged invention. The Patent Ofliice makes no assertion as tothe novelt of the disclosed subject matter.

PUBLISHED JULY 25, 1972 AMMONIUM SULFATE FEEDER 1 seas SCREENS 40-0-0-55(v. AMMONIUM sumra @RECYCLE FINES l m 3 FLOW DIAGRAM OF GRANULATIONPILOT PLANTFOH PRODUCTION OF UREA- AMMONIUM SULFATE A process for theproduction of urea-ammonium sulfate granules from urea and ammoniumsulfate by several granulation methods. The proportion of ammoniumsulfate in the mixture was varied from 15 to 70 percent by weightresulting in products containing from 42 to 2 9 percent N and 3 to 17percent S, respectively. Unexpectedly, the urea-ammonium sulfate mixturein these proportions were fluid enough at 250 to 325 F. to be prilledand granulated by conventional means. Typical grades made incontinuous-type pilot-plant work were 40-0-0-48, 34-0-0-9S, and-0-0-138. Most granulation was carried out by oil prilling or in apugmill but any type of granulation method, such as air prilling or indrum or fiaker, likely would be feasible. With use of 99.5 percent ureasolution and solid ammonium sulfate, no drying step would be required.The presence of the ammonium sulfate increased the strength of thegranules significantly.

No caking occurred when unconditioned 30-009S prills were stored in bulkfor 6 months. Unconditioned product of -0-0-48 grade caked in 3 monthsbut storage for this period was satisfactory when 2 percent by weight ofkaolin clay conditioner was used. The critical relative humidity ofthese products was in the range to percent at 86 F.

Y 1972 H. c. MANN, JR PRODUCTION OF UREA'AMMONIUM SULFATE Filed June 21.1971 .3 Sheets-Sheet 1 i I I I I OPERABLE RANGE [RANGE IN WHICH MIXTURETOO VISCOU AND FOAMY 3 I To PRILL g PRILLABLE TEMPERATURE RANGE E Ill-I5- PREFERRED zoo RANGE 0 I I I I o 20 40 so so I00 AMMONIUM SULFATE I0080 so 40 20 o /0 UREA COMPOSITION I Fm. I

FILLING RANGES OF ON IUM 1. MIXTURES 6 EWM I a July 25, 1972 H. c. MANN,JR

PRODUCTION OF UREA-AMMONIUM SULFATE Filed June 21, 1971 .5 Sheets-Sheet2 l I AIV IMONIUM OFFSIZE FEEDER 7 l0 FLUID MIXTURE OF AMMONIUM SULATEAND UREA r PRILLING VESSEL RECYCLED PRILLING MEDIUM PRILLING OFFSIZE ToFEEDER PROUCT (-s+|2 MESH) PRILLING URE-AMONEUM SULFATE EN LIU!QOM/INVENTOR.

